The present invention is related to shaft lining formula apparatus and particularly to such apparatus for forming vertical or upright monolithic concrete lining in-situ within mine shafts or similar excavations.
In mining operations, central mine shafts, winding shafts, blind shafts, and ventilation shafts are vertical in lead downwardly to and beyond horizontal tunnels. Such shafts may extend from the earth surface vertically downward to other adjoining tunnels, or they may extend from one tunnel vertically to another tunnel at a different elevation. Further, vertical shafts, termed "blind shafts," extend downwardly from one tunnel to a closed bottom end. Nearly all vertical shafts are lined with concrete or masonry to prevent the shaft walls from collapsing and isolating the adjoining tunnels. Various apparatus and methods have been produced for placing shaft linings in such upright open excavations. Most presently used apparatus and methods deal with the application of monolithic concrete lining rather than the application of masonry block or brick work lining.
U.S. Pat. No. 411,981, granted to W. Davis, discloses a method of cementing cisterns or wells. The disclosed process must be performed during the excavation process since the bottom of the shaft is utilized to support a retractable cylindrical form. The excavation is taken to a prescribed depth, then a form is laid in place at the bottom of the excavation. Concrete or cement is then poured about the form and allowed to harden between the form walls and shaft. Once the cement has hardened, the form is removed and the excavation is continued on downwardly past the ring of concrete previously formed. It is intended that this ring be utilized as both a portion of the shaft lining and as a "curbing" to hold the shaft walls intact during the remainder of the excavation operation. It is not disclosed how the shaft walls are lined between the cement rings or "curbing."
U.S. Pat. No. 233,826, granted to W. Wilson on Oct. 26, 1880, discloses an apparatus for lining wells. This device is comprised of two independent form members, one for defining an exterior lining surface and the remaining form for producing the lining interior surface. In operation, after the shaft has been excavated to a required depth, a section of cement tube is placed within the shaft and pressed against the bottom shaft end. This tube must have inside and outside diameters equal to the corresponding dimensions of the lining. Once this tube has been placed within the bottom of the shaft, the inside or core cylinder is lowered into the tube with a portion of its length extending above the top end of the tube. The outer cylinder is also put in place about the outside of the tube and also extends upwardly above the upper tube edge. A tubular receptacle is thereby formed into which cement or concrete may be poured and allowed to harden. Once the cement or concrete has hardened, the two form members may be slipped upwardly over the newly formed lining section to form the next successive batch of concrete poured on top of the previously poured section. In this manner, the well lining is produced in a succession of independent pours from the shaft bottom to top.
The "inchworm" movement of the form members is commonly known as "jump forming" and is typically used in shaft lining operations. This process has been reasonably effective. However, there does exist a line or joint between each successive pouring. Such joints may become weak areas that will allow collapse of the lining if the exterior pressure of the earth surrounding the shaft is excessive. An additional problem with "jump forming," since it involves peak labor periods, is relatively low production rates.
U.S. Pat. No. 1,313,013, granted to C. Polysu, on Aug. 12, 1919, disclosed a method and apparatus for casing wells. This apparatus is somewhat similar to the Davis device in that the lining is formed in a downward direction from the top of the shaft and is formed while the shaft is being excavated. This particular device utilizes a boring head with a concrete slipform following behind. The lining may be poured after the boring instrument has excavated a shaft to a depth equal to the height of the slipform member. The slipform itself is simply an inner core member that forms the inside bore of the lining. Concrete is pumped downwardly to the slipform and outwardly into the area between the slipform and boring head. As the shaft is excavated, the boring head moves downwardly and so does the slipform. Concrete is pumped into the area between the slipform and shaft as the slipform moves downwardly at a rate equal to the rate of excavation for the boring head. At the end of the boring operation the slipform must be left with the shaft since the full weight of the shaft lining rests upon the lower portion thereof. The setting or hardening time of the concrete being delivered to the slipform must be timed precisely with the advancement of the boring tool. Therefore, the conditions of the soil surrounding the shaft area must be very carefully considered and extremely prompt action must be taken when soil conditions change so the lining is not formed at an incorrect rate. For example, if the lining is formed too quickly the concrete will not properly harden and could very easily fall apart once the slipform moves downwardly leaving the wet concrete to support itself. Should the boring head move too slowly, the concrete could harden within the delivery tube and halt progression of the lining at that point.
U.S. Pat. No. 3,827,244, granted to H. Walbrohl on Aug. 6, 1974, discloses a form for producing a concrete lining of mine galleries, tunnels, shafts, or the like. In this instance, a slipform is pulled directly behind a tunneling cutter. It includes a relatively short forming member that receives and forms concrete about its periphery against the tunnel walls and a series of thrust members that are utilized to support the "green" concrete until it reaches a sufficiently stable form to support itself and withstand the pressure exerted by the earth around the tunnel. The thrust members are pulled along with the forming head at a rate such that the last thrust member leaves the concrete lining surface exposed as that surface reaches a hardened condition. It is the "shutters" or reinforcing rib members that are the central subject of this patent, not the specific details of a slipform. The slipform itself is pulled along as it receives concrete in a wet plastic form by a boring mechanism. No disclosure is made as to the utilization of fluid pressure behind the slipform mechanism to "push" the slipform along the shaft or tunnel.
Other patents of general interest are U.S. Pat. No. 3,270,511, granted on Sept. 6, 1966, to E. Colly and U.S. Pat. No. 3,768,267, granted on Oct. 30, 1973 to N. Chlumecky. Also, further background material may be had with reference to my U.S. Pat. No. 3,877,855 granted Apr. 15, 1975.